[Solved] >> 4 or /16 for getting chunk?

[jredfox]

Edit: use >> 4

>> 4 or /16 for getting chunk? I have read that >>4 is more optimized yet it fails on negative numbers I am confused since vanilla uses >>4 when it's negative???? I need it for teleporting entities now because of a vanilla bug with the entities not being added to chunks when teleporting if the chunk isn't loaded(never) or not being added to next tick

	/**
     *supports teleporting entities from location to location in the same dimension doesn't support actual cross dimensional teleport
     */
    public static void doTeleport(Entity e, double x, double y, double z,float yaw, float pitch)
    {
        int chunkOldX = (int)e.posX >> 4;
 	int chunkOldZ = (int)e.posZ >> 4;
        int chunkX = (int)x >> 4;
	int chunkZ = (int)z >> 4;
 	//remove from old chunk
        if(chunkOldX != chunkX || chunkOldZ != chunkZ)
        {
        	Chunk chunkOld = e.world.getChunkFromChunkCoords(chunkOldX,chunkOldZ);
        	chunkOld.removeEntity(e);
        }
 		
        if (e instanceof EntityPlayerMP)
        {
            Set<SPacketPlayerPosLook.EnumFlags> set = EnumSet.<SPacketPlayerPosLook.EnumFlags>noneOf(SPacketPlayerPosLook.EnumFlags.class);
            e.dismountRidingEntity();
            e.setLocationAndAngles(x, y, z, e.rotationYaw, e.rotationPitch);
            ((EntityPlayerMP)e).connection.setPlayerLocation(x, y, z, yaw, pitch, set);
        }
        else
        {
            float f2 = (float)MathHelper.wrapDegrees(yaw);
            float f3 = (float)MathHelper.wrapDegrees(pitch);
            f3 = MathHelper.clamp(f3, -90.0F, 90.0F);
            e.setLocationAndAngles(x, y, z, f2, f3);    
        }
        
        if (!(e instanceof EntityLivingBase) || !((EntityLivingBase)e).isElytraFlying())
        {
            e.motionY = 0.0D;
            e.onGround = true;
        }
        //vanilla hotfix add entity to the new chunk if not already added
        Chunk chunk = e.world.getChunkFromChunkCoords(chunkX,chunkZ);
        if(!containsEntity(chunk.getEntityLists(),e))
        	chunk.addEntity(e);
    }

 

	public static boolean containsEntity(ClassInheritanceMultiMap<Entity>[] list,Entity e) 
	{
		for(int i=0;i<list.length;i++)
		{
			ClassInheritanceMultiMap map = list[i];
			Iterator<Entity> it = map.iterator();
			while(it.hasNext())
			{
				Entity e2 = it.next();
				if(e == e2)
					return true;
			}
		}
		return false;
	}

 

Edited May 17, 2018 by jredfox

[Draco18s]

>> 4
Because of negative coordinates.

 

15 >> 4 = 0 ✓

15 / 16 = 0 ✓

-15 >> 4 = -1 ✓

-15 / 16 = 0 ✗

 

Edited May 17, 2018 by Draco18s

[jredfox]

8 minutes ago, Draco18s said:

>> 4
Because of negative coordinates.

 

15 >> 4 = 0 ✓

15 / 16 = 0 ✓

-15 >> 4 = -1 ✓

-15 / 16 = 0 ✗

 

ok so >>4 or use math helper then?

Edited May 17, 2018 by jredfox

[Draco18s]

WTF?

Edited May 17, 2018 by Draco18s

[jredfox]

2 hours ago, Draco18s said:

WTF?

so your saying it's proper to do division then ? why is there an x there then as if that failed?

[Draco18s]

8 hours ago, jredfox said:

so your saying it's proper to do division then ? why is there an x there then as if that failed?

Jesus Christ, you're as dumb as a post. No, only use >> 4, as I already said twice.

The X is there because it failed to produce the correct result, therefore it is wrong and should not be used.

[jabelar]

JRedFox was agreeing with you. I'm not sure why you said WTF. You said use bit shifting and he said "okay I'll use bit shifting" then you said "WTF".

[Draco18s]

37 minutes ago, jabelar said:

JRedFox was agreeing with you. I'm not sure why you said WTF. You said use bit shifting and he said "okay I'll use bit shifting" then you said "WTF".

The post was edited. I can't view the edit history, but I'm almost certain he said "division" when I made my reply. I've slept since then.

He also has "or MathHelper" in there, and MathHelper does not contain a "BlockToChunk" method (there is exactly one instance of >>4 in it: smallestEncompassingPowerOfTwo), so also wrong.

Edited May 17, 2018 by Draco18s

[jabelar]

8 hours ago, Draco18s said:

The post was edited. 

Okay, makes sense.